1. Fields of the Invention
The invention concerns with improvements in and relating to electrostatic photocopiers capable of operating in the book copy mode and fitted automatic document feeder means and further occasionally with manual paper feeder means.
2. Prior Art
It is well known to those skilled in the art that electrostatic photocopiers may well be fitted with such means which makes the copier functionable in the book copy mode as so called. With such modernized photocopier, an opened book used as the original document of which copies must be prepared is placed on a transparent plate constituting part of the top of the housing of the photocopier proper. When the operator actuates a print button of the machine, the optical system thereof is caused to scan these two open pages of the book successively for the execution of copying jobs on two separate paper sheets.
Therefore, it is unnecessary in this case, to manipulate the copy button for each page of the book, and thus, two successive book pages can be photocopied on respective copying sheets upon only one manipulation of the copy button.
In the case of the book copy mode operative electrophotostatic copiers, it is also known to control the scanning area depending upon the lengthwise dimension of the copying paper sheet (more specifically, the longer size dimension of paper sizes of the format such as A4, B4 or the like reference may be had to FIG. 10 and its related disclosure to follow). In the case of this system, and corresponding to a single manipulation of the copy button, a first page and the following page of an open document book are successively scanned by the optical system of the machine for the execution of the following successive electrostatic photocopying.
On the other hand, the electrostatic photocopier may be provided with a feed opening adapted for receiving copying paper sheets in the manual feed mode. With such an arrangement, any selected size paper is utilized for photocopying.
It is now assumed that when a copying paper is introduced and supplied through such manual paper supply opening, the practically used paper dimension as measured in its lengthwise direction cannot be estimated beforehand. Thus, in this case, the necessary operation control of the book copy mode machine cannot be realized.
On the other hand, electrostatic photocopiers may rather frequently be fitted with respective automatic document feeders, briefly called "ADF". With this improved document feeder, a number of documents to be copied are automatically and successively fed onto the conventional transparent plate. In this case, manual and independent sheetwise positioning of documents can be dispensed with, thus otherwise consuming too much time and labor can be saved to a substantial degree.
However, it should be noted that in this kind of a rather modernized electrostatic photo-copier which is capable of performing a book copy mode photo-copying operation and additionally fitted with ADF-means, if the user should adopt a simultaneous and combined operation of the book copy mode and of the automatic document feed mode, miscopies may be defectively produced. More specifically, in case of the book mode operation, twice scanning operations will be carried out by the optical scanning system for each one photo-copying operation. In the first scanning operation, the document brought onto the transparent plate or the machine proper by the action of the ADF-mechanism, can be copied in the normal and regular way. Upon the completion of the said first scanning operation, the ADF-mechanism adjudges, indeed, that the copying operation has been successfully completed, and the document will be carried away outside of the ADF-mechanism. Thus, there is no document in position when the next succeeding, second scanning operation is caused to initiate. Therefore, in the second scanning operation, the copy paper cannot have any document image. And instead, the copy paper has, indeed, copied images of the ADF-conveyor belt means per se.